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Low Temperature Growth Chambers
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Source：Internet Author：Unknow Pubdate：2010-06-17
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ChrisConley (Mechanical)
27 May 10 15:19
I'm working on a little project where the client would like to hodge together a few growth chambers (rather than purchasing them).
One of the criteria I've been given is to be able to maintain the chamber at 4 deg C (40 deg F) with air at 1 deg C (34 deg F) to prevent freezing the plants.
Within the growth chamber are a number of lights (10 lights at 1000W each), if the lights are on, given the low deltaT I'm working with I end up moving a huge volume of air through a small space (~5300 cfm through an 8x10x10 chamber). The velocity would be the equivalent of standing in an air handler.
The only option I see is to try and supply air below freezing and then induce room air to prevent freezing air from reaching the plants.
Has anyone worked on a similar project? I've already indicated to the client that their criteria may not be possible, but would still like to present them with options.
字串2
imok2 (Mechanical)
27 May 10 18:57
Chris I found this
"Sorry but the most space you should use a 1000w is a 4'x4' area. So two lights = 4'x8' table or 2 4'x4' table. If you put the two 4'x4' tables next to each other or the one 4'x8' table then you could use 3 600w and be using less amps and less electricity but getting the same light and yeilds". at this web sits if your interested. If its true your heat load could be cut 50%
http://www.gardenscure.com/420/lighting/97055-optimal-number-plants-1000w-hps.html
IRstuff (Aerospace)
27 May 10 19:05
One option is to use cold filters on the lamps, and wall off the lamps from the main growth chamber. You'd run massive amounts of air through the light chamber, and that could potentially cut considerably the thermal load in the main chamber. TTFN 字串3
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ChrisConley (Mechanical)
28 May 10 11:00
Thanks imok, I unfortunetly have no control over the lighting design, and when it comes to plant biology I'm out of my element.
We looked at using 'ducted' lights, still need a tremendous volume of air in the space. In addition, the rooms are too small for much ductwork.
Thanks for the comments!
AbbyNormal (Mechanical)
29 May 10 15:42
sounds like you need walk in cooler equipment The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install
SAK9 (Mechanical)
30 May 10 18:34
One approach would be to design the air distribution system in such a way that most of the heat from the lights can be accounted for in the return air heat gain.I have seen this at work in some manufactirung spaces with large equipment loads.
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AbbyNormal (Mechanical)
30 May 10 18:57
SAK
you make it sound like UFAD, displaces the heat outof the space The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install
walkes (Mechanical)
1 Jun 10 11:52
Hey Chris, we are just finishing off 8 growth rooms with similar characteristics, not as cold as yours though. Is the intent to provide that level of cooling with the lights on? In our situation the cooler setpoint (10 to 14°C) was for a night mode.
Our design was based on two heat pumps, one had the capability of maintaining space temperature with the lights on. The second was to assist in dehumidification and driving the temperature down for night mode.
The air is supplied below the plant tables because the lighting system essentially covers the entire space and is on a winch system to vary the distance of the lamps to the plants. Essentially a displacement type of system, the coil handles most of the load through the return air. 字串5
Your situation sounds like you will require some low temp refrigeration though.
Our client revised their requirements such that the temperature was not as critical as the humidity control, so a dessicant type dehumidifier was employed as well.
ChrisConley (Mechanical)
1 Jun 10 11:55
A long talk with the owner resulted in them revising their criteria. My thought was that they were asking for everything they could imagine, and I was right.
The growth chambers have been revised to 15 deg C lights on 10 deg C lights off.
Thanks for the tips everyone.
AbbyNormal (Mechanical)
1 Jun 10 12:35
Moose Jaw Sinsimelian is going to rival British Columbia? The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install
ChrisConley (Mechanical)
1 Jun 10 12:49
字串1
Sorry AbbyNormal, I can't make any sense of your post. I even margin-left:0;margin-right:0;">
AbbyNormal (Mechanical)
1 Jun 10 23:27
I was trying to be funny, its sounds like a grow-op
someone even had a grow op forum link up there.
get a lot of hits on yahoo on the mis-spelling
http://en.wikipedia.org/wiki/Cannabis_cultivation The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install
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